Controlling the boron-to-titanium ratio in magnetron-sputter-deposited TiBx thin films

Abstract

Magnetron sputter-deposited TiBx films grown from TiB2 targets are typically highly overstoichiometric with x ranging from 3.5 to 2.4 due to differences in Ti and B preferential ejection angles and gas-phase scattering during transport between the target and the substrate. The authors show that the use of highly magnetically unbalanced magnetron sputtering leads to selective ionization of sputter-ejected Ti atoms which are steered via an external magnetic field to the film, thus establishing control of the B/Ti ratio with the ability to obtain stoichiometric TiB2 films over a wide range in Ar sputtering pressures.

Synthesis and characterization of (Ti1-Al )B2+ thin films from combinatorial magnetron sputtering

“…Higher accommodation of B is obtained for higher Ti:Al ratios. This is consistent with the previously established overstoichiometry in magnetron sputtered TiB2 thin films [25,26]. On the other hand, lower Ti:Al ratio, i.e., more Al, correlates with an increased incorporation of O.…”

Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1−xTaxBy thin films

“…35 An increase in the substrate bias can also lead to a limited decrease in the B/TM ratio as a result of preferential B resputtering. 36 A successful approach for obtaining stoichiometric TiB2 films was recently demonstrated by Petrov et al, 37 who used highly-magnetically-unbalanced magnetron sputtering of a TiB2 target in Ar to selectively ionize sputter-ejected Ti atoms, which are steered via a tunable external magnetic field to the growing film. The B/Ti ratio was thus controlled by varying the field strength of external Helmholtz coils.…”

Multifunctional transition metal diboride thin films grown by magnetron sputtering with metal-ion irradiation

“…A successful approach for obtaining stoichiometric TiB2 thin films was recently proposed based on the use of highly-magnetically-unbalanced magnetron sputtering of a TiB2 target in Ar atmosphere to selectively ionize sputter-ejected Ti atoms, which are then steered via a tunable external magnetic field to the growing film. The B/Ti ratio is thus controlled by varying the field strength of external Helmholtz coils [52]. However, this technique requires external magnetic coils, which is not compatible with industrial deposition systems.…”